Agricultural field sprayers are known in which the pumps used to convey sprayer fluid are driven hydraulically or mechanically. In the case of towed sprayers a tractor power take-off shaft or hydraulic motors driven from a hydraulic source on the tractor provide power. Pumps driven in such a way are usually operated at a constant pump rotational speed so that constant amounts of fluid are conveyed. The amounts conveyed or the flow rates are varied by means of bypass valves to adjust the flow rate required for a particular application. The variation can be a function of the area of the sprayer gear or a partial area adjustment, or a selected operating velocity or a desired amount of sprayer fluid. In addition to the actual application of the sprayer fluid, the flow rate generated by the pump or the volume flow generated by the pump also functions to circulate the contents of the tank and assure a uniform concentration of the sprayer fluid in the constant rate of flow. Depending on the type and composition of the sprayer material, an excessively large flow rate could be applied that could lead to foaming of the sprayer fluid, particularly if only a residual amount of sprayer fluid is contained in the tank. Furthermore it is usual practice and may also be required by law to perform a cleaning of the sprayer on the field in order to remove residual amounts of sprayer fluid in the tank and in the fluid line system. The position of the pump plays a major role in the rate of cleaning that can be attained, and positioning of the pump close to the tank is advantageous. Due to limitations of the configuration resulting from conventional pumps being driven by power takeoff shafts, rates may be insufficient for proper of cleaning of the system.